1. Allen, T.F.H., Starr, T.B., 1982. Hierarchy. Perspectives for Ecological Complexity. University of Chicago Press, Chicago, IL.
2. Anonymous, 1994. Britain's very own Brundtland strategy. Nature 367, 395–396.
3. Bailey, K.D., 1990. Social Entropy Theory. State University of New York Press, Albany, NY.
4. Sustainable development: Is it a useful concept?;Beckerman;Environ. Values,1994
5. Bertalanffy, L. von, 1968. General System Theory. Foundations, Development Applications. George Braziller, New York.